Carbon catalysts have shown promise as an alternative to the currently available energy-intensive approaches for nitrogen fixation (NF) to urea, NH3, or related nitrogenous compounds. The primary challenges for NF are the natural inertia of nitrogenous molecules and the competitive hydrogen evolution reaction (HER). Recently, carbon-based materials have made significant progress due to their tunable electronic structure and ease of defect formation. These properties significantly enhance electrocatalytic and photocatalytic nitrogen reduction reaction (NRR) activity. While transition metal-based catalysts have solved the kinetic constraints to activate nitrogen bonds via the donation-back-π approach, there is a problem: the d-orbital electrons of these transition metal atoms tend to generate H-metal bonds, inadvertently amplifying unwanted HER. Because of this, a timely review of defective carbon-based electrocatalysts for NF is imperative. Such a review will succinctly capture recent developments in both experimental and theoretical fields. It will delve into multiple defective engineering approaches to advance the development of ideal carbon-based electrocatalysts and photocatalysts. Furthermore, this review will carefully explore the natural correlation between the structure of these defective carbon-based electrocatalysts and photocatalysts and their NF activity. Finally, novel carbon-based catalysts are introduced to obtain more efficient performance of NF, paving the way for a sustainable future.@en

The invention of hydroelectric nanogenerators (HENGs) is a breakthrough technology for green electricity generation. However, the underlying mechanisms driving energy conversion remain largely unknown, impeding the development of HENGs with high energy densities. Here, we develop a new Multiphysics model involving Darcy's law, phase transfer in porous media, and current modules to reveal the mechanisms of electricity generation in HENGs. This is the first model to simulate evaporation as a streaming potential variable with the Robin-type boundary condition that overcomes the shortcomings of Neumann- and Dirichlet-type boundary conditions. Including the streaming potential and electric double layer (EDL) effects, the simulation can be based on actual water flow conditions, which is more convincing and lays a microscopic foundation for future research and exploration into the mechanism of hydroelectric electricity generation. The new model reveals that the concentrations of salt solutions significantly impact the output power density of HENGs by affecting the solution conductivity in the stern layer, while relative humidity has a minimal impact. This model along with experimental validation offers a robust method to improve the electrical output of HENGs.@en